An independent review has been ordered into the death of a four-year-old boy on the NSW Central Coast as court documents confirm police are investigating cannibalism in the case.

The child’s mother, 32, is accused of his murder, with revelations emerging that child protection workers had reportedly visited the family three times during the boy’s short life.

WATCH THE VIDEO ABOVE: Central Coast child death sparks system failure inquiry

Know the news with the 7NEWS app: Download today

The Wyong community came together on Monday to remember the boy described as “a little angel”, bringing gifts and prayers to honour his memory.

“Your heart breaks because you just see those families, they feel it,” local resident Naomi Hura said. “There’s so many people that are feeling the situation right now.”

That situation was made harder on Monday with news police have carried out tests on the boy’s mother for cannibalism, ordering special swab and DNA analysis.

NSW Families and Communities Minister Kate Washington refused to comment on claims the 32-year-old had drug-induced psychosis.

“There are many complexities involved in this case and I do not want to prejudice the criminal investigation that’s underway,” she said.

Washington denies her department is losing control despite thousands of cases slipping through the cracks, with shadow minister Natasha Maclaren-Jones claiming close to 150,000 young people who had reports presented not seen by a caseworker.

The independent review will investigate how department workers acted and why, given the history, the child was living with the mother and whether more could have been done.

“I intend to publicly release the review subject to any legal constraints,” Washington said.

The boy’s mother will spend Monday night in Silverwater Prison after being moved from Kariong Correctional Centre.